Magnetite Fe3O4 nanoparticles and hematite α-Fe2O3 uniform oblique hexagonal microdisks, drum-like particles and spindles and their magnetic properties

Magnetite Fe3O4 nanoparticles and uniform hematite (alpha-Fe2O3) oblique hexagonal microdisks, drum-like particles, and spindles have been synthesized via a facile hydrothermal reaction route, in which the mixture solvents of ethylene glycol (EG) and water are used as reaction medium. The phase, size, shape and growth orientation of the synthesized iron oxide crystals were characterized by powder X-ray diffraction and electron microscopy. When the reaction medium is almost composed of EG, a lot of Fe3+ ions reduce to Fe2+ ions due to the effect of EG, resulting in the magnetite Fe3O4 nanoparticles. As the volume ratio of EG/water in the reaction medium is lower than 30:10, the reductive ability of EG is too low to reduce the Fe3+ ions to Fe2+ ions, leading to the hematite alpha-Fe2O3 crystals. Moreover, since the adsorption of EG on the crystals, the shape of the obtained hematite alpha-Fe2O3 crystals evolves from oblique hexagonal microdisks to drum-like particles, and spindles due to the decrease of EG in the mixture reaction medium solvent. The magnetic properties of the magnetite Fe3O4 nanoparticles and hematite alpha-Fe2O3 uniform microcrystals were also investigated by measuring the magnetic hysteresis loops. (C) 2014 Elsevier B.V. All rights reserved.